(a) Field of the Invention
The present invention is to utilize an active pulley driven by a power source having unidirectional rotating output feature, or to install a unidirectional transmission device installed between the active pulley and a machine body or between an active wheel shaft combined with the active pulley and the machine body, so when a transmission belt is tightened while the active pulley driving a passive pulley in periodically varied speed ratios, meanwhile an auxiliary pulley (312) of an auxiliary pulley assembly for storing/releasing kinetic energy (700) is linked for storing energy to form a prestressed force, when the force applied by the active pulley to the passive pulley through the transmission belt is zero or relatively smaller, the auxiliary pulley (312) is enabled to release energy for recovering so as to apply force to the transmission belt, because the transmission belt is coupled to the active pulley and/or one end of the active wheel shaft combined with the active pulley is restrained by the unidirectional transmission device, the transmission belt is enabled to link the passive pulley to operate in the original revolving direction for feeding back the kinetic energy.
(b) Description of the Prior Art
A conventional transmission pulley set composed of an active chain wheel, a passive chain wheel and a transmission chain, or a transmission pulley set composed of an active tooth-shaped wheel, a passive tooth-shaped wheel, a tooth-shaped transmission belt or a tooth-shaped transmission chain both have features as followings: 1) a non-sliding synchronous transmission feature is formed between the active chain wheel and the passive chain wheel and the transmission chain, or between the active tooth-shaped wheel and the passive tooth-shaped wheel and the tooth-shaped transmission belt or the tooth-shaped transmission chain; (2) if the length of the transmission chain or the tooth-shaped transmission belt or the tooth-shaped transmission chain is changed during the operation or during switching the speed ratio, a prestressed auxiliary idle wheel is often installed for randomly adjusting the tightness of the transmission chain, the tooth-shaped transmission belt or the tooth-shaped transmission chain, however, the tightness of transmission chain would be periodically varied during the operation, so the prestressed mechanism of the auxiliary idle wheel for storing/releasing kinetic energy is reciprocally displaced for storing energy and releasing energy, wherein one disadvantage of the prior art is that the increased load generated at the active side while the transmission chain pressing the auxiliary idle wheel cannot be fed back as a kinetic driving energy.